Pregnancy Due Date Calculator
Free pregnancy due date calculator: LMP with irregular cycle adjustment, ultrasound, or IVF transfer. Week-by-week calendar with milestones. No signup.
Updated June 2026
These calculations are clinical estimates based on standard methods (Naegele's Rule, ACOG guidelines). This tool does not replace medical advice. Always consult your doctor or midwife.
Enter your dates above to calculate your due date and see your pregnancy calendar.
How to Use This Due Date Calculator
Estimate your due date in three steps, using three medical dating methods
1. Choose your dating method
By last menstrual period (LMP) using Naegele's Rule, first-trimester ultrasound (CRL measurement), or IVF embryo transfer date.
2. Enter your dates
LMP with cycle-length adjustment, ultrasound date and gestational age, or transfer date and embryo type (Day 3 or Day 5).
3. Read your results
Gestational age, due date, pregnancy progress, baby size, and a full week-by-week milestone calendar appear instantly.
What This Pregnancy Calculator Does
Cycle-length adjustment most due date calculators skip
Irregular cycle adjustment
Corrects your due date for cycles longer or shorter than 28 days — most online calculators assume exactly 28 days with no exception.
Three dating methods in one tool
LMP with Naegele's Rule, first-trimester ultrasound (CRL), and IVF embryo transfer (Day 3 and Day 5), each with its own correct formula.
Standard medical terminology
Uses LMP, EDD, GA, and CRL — the same abbreviations your OB or midwife uses on your chart.
Week-by-week calendar
Milestones, recommended screening windows, and baby size by fruit comparison for every week of pregnancy.
Due Date Calculation Examples
How the estimate shifts by dating method and cycle length
When You'll Reach for This Tool
The most common scenarios among people using this calculator
Irregular cycles or PCOS
Adjust the cycle-length slider for a more accurate estimate than the standard 28-day formula assumes.
IVF pregnancy
Covers both Day 3 and Day 5 transfers with the correct offset formulas — different from Naegele's Rule applied to the LMP.
Confirming your due date after an ultrasound
Enter the gestational age measured by CRL to get the EDD your OB will record on your chart.
Planning parental leave
The calendar flags week 36 and the key screening windows so you can time your leave request.
Common Mistake? Start Here
Using the LMP without adjusting for cycle length
Without correcting for cycles other than 28 days, the estimate can be off by one to two weeks.
Confusing fetal age with gestational age
GA is counted from the LMP, not conception — "4 weeks" in GA means the embryo itself is only about 2 weeks old.
Expecting labor exactly on the due date
Only about 5% of babies are born on their exact due date. The normal full-term window runs from week 37 to week 42.
Why Use This Due Date Calculator
The cycle-length adjustment is what sets it apart: a 35-day cycle left unadjusted produces a due date that's 7 days too early — an error most online calculators make silently by assuming everyone ovulates on day 14.
It covers all three clinical dating methods (LMP, ultrasound, IVF) with standard medical terminology, and your dates never leave your browser.
How This Compares to Other Due Date Calculators
Cycle adjustment and dating methods side by side
Frequently Asked Questions
Add 280 days to the first day of your last menstrual period. For cycles other than 28 days, adjust by the difference — for example, with a 35-day cycle: EDD = LMP + 287 days.
References
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